porting help on a ms 441 jug

[mark09]

I dont understand just how the strado ports work . I want to widen the intake port but the windows in the piston will be open to the intake port when the intake port is closed putting air fuel mix in the windows. The windows line up with the strado ports in the rotation as well. I thought the strado ports opened just before the transfurs to blow the exhaust out before the new charge came in. so what do the windows have to do with anything? the windows also line up with the transfurs in the rotation. i dont want to have the intake be letting fuel in when the intake is closed threw the windows. the strado ports are lower than the bottem exhaust port so that makes me confused? any help is grate I have ported a dozzen saws but this strado thing is all new to me. the intake is 16 mm wide and the skirt on the piston is 20 mm wide and then the windows are thare on a 52 mm piston

 

[mdavlee]

The strato ports let fresh air in along with the intake letting air/fuel mix in. I've never worked on a 441 but I would imagine matching the strato port and intake port timing should help some.

 

[Mastermind]

The strato ports let fresh air in along with the intake letting air/fuel mix in. I've never worked on a 441 but I would imagine matching the strato port and intake port timing should help some.

Unlike most husky designs the Stihl strato doesn't have a removable transfer cover. This makes it impossible to time the strato ports.

Adding a few degrees to the intake will help the 441 though.

 

[LegDeLimber]

Wondering if a fellow could use an intake plate (press/vac test rig) an a few/ low psi air
and if ya got it, a flow meter (welding rig).
build/block off the plate so that folw is only going to one of strato ports at at time.
whilst very slowly turning the motor watch the gauges, they oughta tell when gross changes occur.
midfull that at slow moving speed you'll get som flow change above rings yet below crown .
So it would be a hearing and gauge watching skill to develop.
bet a dose of thick oil could even help wth the crown to ring zone thing, maybe do test both ways and average out the numbers.
or run a high brightness LED on wires into strat opening and watch through spark plug hole.
might have to do it in semi dim room light or use a small tube/hose to shield your eye from room light, to see that little first - last glimmer.
-
..or what about probing with that fiber optic tip for your favorite flashlight.
or cyl on side, port up, fill with light oil and turn slow, watch for drain off into cylinder.

...course the "rich" guys will just go buy a bore camera.

glad you guys have gotten me to start thinking on this.
now if I'm lucky and some hairbrained idea work, maybe some knowledgeable sharpster
will tip me off on some numbers for my pull-on wead beater.

 

[Wild Knight]

Some relevant posts

Did this a while back. Bits of info scattered throughout the threads:

http://www.arboristsite.com/chainsaw/122658-2.htm
http://www.arboristsite.com/chainsaw/123086.htm
http://www.arboristsite.com/chainsaw/123063.htm
http://www.arboristsite.com/chainsaw/114531-14.htm#post1822372

 

[Mastermind]

And a thread I did on the MS441CRM

http://www.arboristsite.com/chainsaw/195532.htm